Inflator With Reactive Tire Pressure Monitoring

ABSTRACT

A wheel inflation apparatus including a wheel engagement unit that suspends a tire/wheel assembly and at least one inflation unit coupled to the robotic arm, each inflation unit being configured to inflate the tire/wheel assembly. A load measuring unit is configured to sense an amount of load being applied to the wheel/tire assembly. A controller is coupled to the load measuring unit for receiving a load signal and determining an internal air pressure of the tire/wheel assembly based on the load signal. The controller controls the at least one inflation unit based on the determined internal air pressure and a target (desired) air pressure value.

RELATED APPLICATION

This U.S. patent application claims priority to U.S. Provisional Application 61/865,368 filed on Aug. 13, 2013.

TECHNICAL FIELD

This disclosure relates to an apparatus and method for inflating a wheel/tire assembly with reactive tire pressure monitoring.

BACKGROUND

A wheel/tire assembly can be assembled as part of automated process. During assembly, a robot can move a wheel to a mounting station, where the wheel is mounted onto the tire. The robot can also move the wheel with the tire mounted thereon, to an inflation station, where the wheel/tire assembly is inflated. The wheel/tire assembly can then be moved to a balancing station where the wheel/tire assembly is balanced. Each step takes time to perform and each station takes space in an assembly plant.

DESCRIPTION OF DRAWINGS

FIGS. 1A, 1B and 1C are schematic drawings illustrating example components of an inflator with reactive tire pressure monitoring.

FIG. 2 is a flow chart illustrating an example set of operations for a method for operating a reactive tire pressure device.

FIG. 3 is an enlargement showing the interaction of the inflation probe with its environment during the inflation process.

FIG. 4 is a schematic drawing of the force created during the inflation process and how those forces result on the strain sensed by load cell.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIG. 1A illustrates an example robotic inflator with reactive tire pressure mounting 10. According to some implementations, the inflator 10 includes a wheel engagement unit 12, a load cell 14, one or more inflation units 16, a cylinder 24, a cylinder rod 26, and a controller 30. The inflator 10 can include additional or alternative components.

The wheel engagement unit 12 is configured to engage a wheel 42 of a wheel/tire assembly 40. A tire 44 is mounted onto the wheel 42 at a first station. The first station may be at a first location, or the first station (as well as other stations) may be movable with respect to the wheel/tire assembly 40 and the wheel engagement unit 12. Prior to or after the tire 44 is mounted onto the wheel 42, the wheel engagement unit 12 engages the wheel 42. In some implementations, the wheel engagement unit 12 includes one or more mechanisms 13 that are inserted into the center hub and/or the lug-nut holes. The wheel engagement unit 12 may include alternative or additional means for engaging the wheel 42. For example, the wheel engagement unit 12 may include magnetized screws or pins that are inserted into the center hub and/or the lug-nut holes or a magnetized surface that attracts the center hub. The engagement unit 12 is capable of grabbing and lifting the tire/wheel assembly 40 away from platform 11.

Each inflation unit 16 is configured to inflate the wheel/tire assembly 40. In the illustrated example, the inflator 10 may include two inflation units 16, 16′. It is noted, however, that the inflator can include a single inflation unit 16 or more than two inflation units 16, 16′ as well. In some implementations, an inflation unit 16 includes an inflation probe 18 (which is connected to a compressed air source such as an air compressor 19 or similar device) a probe stirrup 20, an inflator actuator 22 and a stirrup actuator 23. The probe stirrup 20 can include a cavity 21 that is larger in at least one dimension than the inflation probe 18 thereby permitting the inflation probe 18 to pass freely through the cavity 21. The probe stirrup 20 can be made of a rigid material (e.g., steel) that can withstand the force of the tire 44 forcibly abutting the portion of the probe stirrup 20 forming the cavity. In operation, a stirrup actuator 23 can linearly actuate a probe stirrup 20 at least along one axis into the tire/wheel assembly 40, such that the probe stirrup 20 is inserted in the gap between the wheel 42 and the tire bead 46 of the tire 44. FIG. 1B illustrates an example where the probe stirrup 20 has been inserted (by actuator 23) between the wheel and the sidewall 46 of the tire 44. Prior to the inflation of the wheel/tire assembly 40, the probe stirrup 20 can be easily placed in between the tire bead 46 and the wheel 42. Thereafter, the inflator actuator 22 manipulates the inflation probe 18 through the cavity of the probe stirrup 20. In this way, the probe stirrup 20 prevents the inflation probe 18 from being pinched between the wheel 42 and the tire bead as a result of the increasing internal air pressure of the tire 44 during inflation. FIG. 1C illustrates an example of the inflation probe 18 being located in the cavity of the probe stirrup 20. Once the inflation probe 18 is inserted into the cavity of the probe stirrup 20, the air compressor (not shown) can be commanded to begin pumping air into the wheel/tire assembly 40.

Now referring to FIG. 4, the load cell 14 outputs an electrical signal along conductor 15 indicating a measure of strain that is sensed across load cell 14 (i.e. F′_(A)+F′_(B)). The amount of strain that is sensed corresponds, in part, to the force F′_(A) (exerted by the tire 44 against probe 18, 18′ and probe stirrup 20, 20′) and force F′ _(B) (exerted by the tire 44 against lower wheel bead 41, 41′ of wheel 42. The force exerted by the tire against 18, 18′, 20, 20′, 41, 41′ is, at least in part, a function of the internal air pressure within wheel/tire assembly 40. In some implementations, the internal air pressure within cavity 45 of the wheel/tire assembly 40 results in an upward force being applied to the inflation probe 18 and/or the probe stirrup 20 as the wheel/tire assembly 40 is inflated. In these implementations, the upward force is transferred to the load cell 14 via rigid support structure 21, 21′. In some implementations, the upward force F′_(A) may be transferred to the load cell 14 by way of the cylinder 24, which transfers the upward force to the cylinder rod 26. The cylinder rod 26 can transfer the upward force to the load cell 14. Additionally or alternatively, the air pressure within air cavity 45 of the wheel/tire assembly 40 may result in a downward force F′_(B) being applied to the wheel/tire assembly 40 as the wheel/tire assembly 40 is inflated. The downward force is transferred to the wheel engagement unit 12, which in turn transfers the downward force onto the load cell 14. In this way, as the inflation probe 18 inflates the wheel/tire assembly 40, the upward force and the downward force act simultaneously on the load cell 14. The arrows 50 and 52 depicted FIG. 1C are examples of the forces acting upon the load cell 14. The load cell 14 outputs a signal indicating a magnitude of the force. In an embodiment, inflation units 16, and 16′ are spaced apart from and do not contact any part of wheel 42. This spaced relationship (gap) enhances the accuracy of the system by eliminating any of the reaction force F_(AN) from being drawn away from load cell 14. In an embodiment, during the inflation process, wheel engagement unit 12 is the sole means of supporting tire/wheel assembly 40 (i.e. platform 11 does not engage assembly 40).

The load cell 14 can measure the magnitude in any suitable manner. In some implementations, the load cell 14 includes a strain gauge that measures the magnitude of the force based on a change of resistance of a resistor when a force is applied and distorts the resistor. Additionally or alternatively, the load cell 14 can be a hydraulic load cell that measures the magnitude of the force based on a displacement of a liquid caused by the upward and downward forces acting upon the load cell.

The controller 30 can be a one or more processors, microprocessors, and/or ASIC circuits that control operation of the inflator 10. In some implementations, the controller 30 executes machine-readable instructions for controlling the inflator 10. The controller 30 can control actuators and/or motors that cause the motion of the wheel engagement unit 12, the inflation unit 16, the cylinder rod 24, and the cylinder. Furthermore, the controller 30 can determine the internal air pressure of the wheel/tire assembly 40 based on the output signal 15 of the load cell 14. In some implementations, the controller 30 determines the air pressure based on a lookup table. The look table can be generated heuristically, such that air pressure values can be correlated to various combinations of force measurements and/or tire parameters (e.g., tread type, tire type, wheel size). Additionally or alternatively, the air pressure can be determined according to a predetermined equation where air pressure is a function of the force measurement and, possibly, one or more tire parameters. When the internal air pressure reaches a threshold, e.g., 32 psi, the controller 30 commands the inflation unit 16 to withdraw from the wheel/tire assembly 16.

In some implementations, the cylinder 24 mechanically moves the inflator 10 from a first position to a second position. The movement of the cylinder 24 can be controlled by one or more actuators or motors that move the cylinder 24 in one or more directions. For example, the cylinder 24 can be controlled by an actuator or motor to move the inflator 10 from a tire mounting station to a wheel balancing station. At the control of the actuator or motor, the cylinder 24 can raise and lower the wheel engagement unit 12 and can also move the wheel engagement unit 12 horizontally. In some implementations, the wheel/tire assembly 40 is inflated while the cylinder 24 is moving the wheel/tire assembly 40 from the first location to the second location.

Additionally or alternatively, the cylinder 24 raises the wheel/tire assembly 40 and various stations (e.g., wheel mounting and wheel balancing stations) are moved to the location of the wheel/tire assembly 40. In these implementations, the inflation unit 16 inflates the wheel/tire assembly 40 while the cylinder 24 is raising the wheel/tire assembly 40.

In some implementations, the cylinder rod 26 raises and lowers the wheel engagement unit 12. Furthermore, in some implementations, the cylinder rod also rotates the wheel engagement unit 12 to engage the hub and/or the lug-nut holes. The movement of the cylinder rod 26 can be controlled by one or more actuators and/or motors.

The inflator 10 of FIG. 1 is provided for example only. Alternate configurations of the inflator 10 are contemplated and are within the scope of the disclosure. For instance, the inflation unit 16 may be configured to inflate the wheel/tire assembly 40 via an inflation valve (not shown) disposed along the wheel 42 or tire 44. In these implementations, the load cell 14 would operate in substantially the same manner, but the upward force would be transferred from the inflation valve.

FIG. 2 illustrates an example set of operations that can be performed by the controller 30 according to some implementations of the present disclosure. It is noted that in alternate configurations of the inflator 10, the operations may be varied accordingly.

At operation 210, the controller 30 commands an actuator or motor connected to the cylinder 24 to move the cylinder to a first location. The first location may be a station on an assembly line of the wheel/tire assembly (e.g., a tire mounting station).

At operation 212, the controller 30 causes the wheel engagement unit 12 to engage the wheel/tire assembly 40. The controller 30 can command the actuator and/or motor connected to the cylinder rod 26 to move the wheel engagement unit 12 into position to engage the wheel/tire assembly 40. Once the wheel engagement unit 12 is in position to engage the wheel/tire assembly 40, the controller 30 can command the actuator and/or motor connected to the cylinder rod to move the wheel engagement unit 12 into an engaged position (e.g., rotate the wheel engagement unit 12 such that the wheel/tire assembly 40 is mounted onto the wheel engagement unit 12).

At operation 214, the controller 30 causes the cylinder to begin moving the wheel/tire assembly 40 from the first location to a second location. The second location can be another station on the assembly line, such as a wheel balancing station. The controller 30 can move the wheel/tire assembly 40 by, for example, commanding an actuator or motor connected to the cylinder 24 to move the cylinder in a direction of the second location.

At operation 216, the controller 30 causes the inflation probe 18 to be inserted into the wheel/tire assembly 42. In some implementations, the controller 30 commands the stirrup actuator 23 to slide the probe stirrup 20 into a position between the wheel 42 and the tire 44 (i.e., at the side wall 46 of the tire 44). Once the probe stirrup 20 is in position, the controller 30 commands the inflator actuator 22 to move the inflation probe 18 into the cavity of the probe stirrup 20. Once, the inflation probe 18 is in the cavity of the probe stirrup 20, the inflation probe 18 is in position to inflate the tire. The foregoing operation can be performed for each inflation unit 16. FIG. 3 illustrates an example of the inflation probe 18 being in position to inflate the wheel/tire assembly 40. As illustrated, a distal end 300 of the inflation probe 18 is disposed in the cavity 302 of the probe stirrup 20. At operation 218, the controller 30 commands the air compressor 19 to inflate the wheel/tire assembly 40.

At operation 220, the controller 30 can determine an air pressure in the wheel/tire assembly 40. In some implementations, the controller 30 receives the air pressure measure from the controller 30. In some implementations, the controller 30 receives a signal indicating the force being applied to the load cell 14 and calculates the air pressure based on the signal. The controller 30 can calculate the air pressure according to a lookup table or a predetermined equation.

At operation 222, the controller 30 determines whether the determined air pressure is less than a threshold. The threshold is indicative of a desired air pressure in the wheel/tire assembly 40. If the air pressure is less than the threshold, the controller 30 continues to command the air compressor 19 to inflate the wheel/tire assembly 40. Otherwise, when the air pressure equals or exceeds the threshold, the controller 30 causes the inflation probe 18 to be removed from the wheel/tire assembly, as shown at operation 224. In some implementations, the controller 30 commands the inflation actuator 22 to retract the inflation probe 16 and then commands the probe actuator 23 to retract the probe stirrup 20. At operation 226, the movement of the wheel/tire assembly 40 to the second location is completed. The controller 30 can continue to command the actuator or motor of the cylinder 24 to move the cylinder 24 until the wheel/tire assembly 40 reaches the second location. The controller 30 may further command the wheel engagement unit 12 to disengage the wheel/tire assembly 42.

Variations of the method 200 are contemplated and are within the scope of the disclosure. Furthermore, depending on the assembly of the inflator 10 (e.g., whether the wheel/tire assembly 10 is moved from a first station to a second station or whether the first station and the second station are movable with respect to the wheel/tire assembly 40), some operations may be varied, replaced, or removed. 

What is claimed is:
 1. A wheel inflation apparatus, comprising: a wheel engagement unit that suspends a tire/wheel assembly; at least one inflation unit coupled to the robotic arm, each inflation unit being configured to inflate the tire/wheel assembly; a load measuring unit configured to sense an amount of strain being applied to the wheel/tire assembly; a controller that receives a load signal from the load measuring device, determines an internal air pressure of the tire/wheel assembly based on the signal, and controls the at least one inflation unit based on the determined internal air pressure.
 2. The apparatus of claim 1, wherein each inflation unit includes a probe stirrup and an air inflation probe, the air inflation probe being insertable into the probe stirrup.
 3. The apparatus of claim 2, wherein each of the at probe stirrup and the air inflation probe is linearly actuatable.
 4. The apparatus of claim 1, wherein the load measuring unit is a hydraulic based load cell measurement transducer.
 5. The apparatus of claim 1, wherein the load measuring unit is a strain gauge based load cell measurement transducer.
 6. The apparatus of claim 1, wherein the pressure determination module includes an electronic circuit that accepts an electrical signal generated by the load measuring device and translates the signal into a signal that is indicative of the inflation pressure present within the tire/wheel assembly.
 7. The apparatus of claim 1, further comprising a robotic arm configured to move the wheel engagement unit between a first station and a second station.
 8. The apparatus of claim 7, wherein the controller controls the at least one inflation unit to inflate the wheel/tire assembly while the robotic arm is moving the wheel/tire assembly from the first station to the second station.
 9. A method comprising: inflating a wheel/tire assembly with at least one inflation unit; during inflation, monitoring a load cell to determine an amount of force applied to the wheel/tire assembly as a result of the inflating; determining an internal air pressure of the wheel/tire assembly based on the amount of force; and determining whether to continue inflating based on the internal air pressure.
 10. The method of claim 9, further comprising: engaging the wheel/tire assembly prior to the inflating; and moving the wheel/tire assembly from a first location to a second location, wherein the inflating is performed during the moving.
 11. The method of claim 9, wherein determining the internal air pressure includes looking up the internal air pressure from a look up table that associates air pressure values with varying force measurements.
 12. The method of claim 11, wherein the look up table further associates air pressure values with parameters corresponding to different types of wheels, tires, and/or wheel/tire assemblies.
 13. The method of claim 9, where each inflation unit includes a probe stirrup and an air inflation probe, the air inflation probe being insertable into the probe stirrup.
 14. The method of claim 13, wherein the load cell monitors a first force applied to the load force via the wheel/tire assembly and a second force applied to the load cell via a robotic arm to which the at least one inflation unit is coupled to, such that the first force and the second force are substantially opposite in direction.
 15. An air pressure measuring device for measuring the air pressure of a tire/wheel assembly, comprising: support member for engaging and supporting a tire/wheel assembly; one or more reaction members engaging an outer surface of the tire; a load measuring device having first and second ends, wherein said first end is in communication with said support member, and wherein said second end is in communication with said one or more reaction members; and load to tire pressure conversion unit coupled to said load measuring device for accepting an output signal which is indicative of a load sensed by said load measuring device and converting the signal to a value representative of the inflation air pressure present within the tire/wheel assembly.
 16. The air pressure measuring device of claim 15, wherein the one or more reaction members include at least one of a probe stirrup and an air inflation probe.
 17. The air pressure measuring device of claim 15, wherein the load measuring device is a strain gauge based load cell measurement transducer.
 18. The air pressure measuring device of claim 15, wherein the load measuring device is a hydraulic sensing device for sensing load.
 19. The air pressure measuring device of claim 15, wherein load to tire pressure conversion unit includes an electronic circuit for accepting an electrical signal generated by said load measuring device and translating that signal into a signal that is indicative of the inflation air pressure present within the air cavity tire/wheel assembly. 